If you're making an ash longbow, with a D-cross section and a bend-through-the-handle design (like the MR bows), I strongly recommend you heat treat the belly of the bow. (Unless you have a piece of ash with SG 0.9 or higher). Unless you have a piece of wood with this good SG, ash bows of this design and draw weights in the warbow category have a bad habit of following the string.
Also remember to make sure you have a water proof finish on ash bows. Add it while the MC is as low as 7-8% to get the best result from ash. (Ash is really good at soaking up water

)
-But made the right way, ash can take heavy poundage, good performing bows.
Look forward to see the result!